Impara Introduction to String Functions

When working with text data in SQL, string functions are essential tools that let you transform, analyze, and extract information from character fields. These functions help you clean up messy data, standardize text formats, and create new values based on existing information. Whether you need to change the case of names, count the number of characters in an email address, or build custom strings for reports, string functions make these tasks simple and efficient.


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-- Transform and analyze customer names using string functions
SELECT
  name,
  UPPER(name) AS name_uppercase,
  LOWER(name) AS name_lowercase,
  LENGTH(name) AS name_length
FROM customers;

You can combine multiple string functions in a single query to perform advanced text processing. For instance, you might want to convert a name to lowercase and then count its characters, or standardize email addresses by joining different pieces of data together. By nesting and chaining functions, you gain powerful ways to reshape and analyze your text data directly within SQL.


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-- Create custom email usernames by combining and extracting strings
SELECT
  name,
  CONCAT(LOWER(SUBSTRING(name, 1, 1)), LOWER(SUBSTRING(name, POSITION(' ' IN name) + 1, 5))) AS custom_username
FROM customers;

1. Which function changes all characters in a string to uppercase?

2. Which SQL function extracts a substring from a given string?

3. Fill in the blanks to select the length of each customer's name after converting it to lowercase.

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Sezione 1. Capitolo 1

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Suggested prompts:

Can you explain how the custom_username is generated in the SQL query?

What other string functions can I use to manipulate text in SQL?

Can you show more examples of combining string functions in SQL?

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